# After the warmup period, set the desired wavelength with the Wavelength Control Knob.

# After the warmup period, set the desired wavelength with the Wavelength Control Knob.

# Set the filter lever to the appropriate position for the selected wavelength (not required for SPECTRONIC® 20).

# Set the filter lever to the appropriate position for the selected wavelength (not required for SPECTRONIC® 20).

-

# Adjust the meter to 0%T with the Power Switch/Zero Control (knob on the front left side

+

# Adjust the meter to 0%T with the Power Switch/Zero Control (knob on the front left side of instrument). Make sure the sample compartment is empty and the cover is closed.

-

of instrument). Make sure the sample compartment is empty and the cover is closed.

+

# Fill a clean cell with water (or blank solution) and wipe the cell with a tissue to remove liquid droplets, dust and fingerprints.

-

# Fill a clean cell with water (or blank solution) and wipe the cell with a tissue to remove liquid

+

# Place the cell in the sample compartment and align the guide mark on the cell with the guide mark at the front of the sample compartment. Press the cell firmly into the sample compartment and close the lid.

-

droplets, dust and fingerprints.

+

# Adjust the meter to 100%T with the Transmittance/Absorbance Control (knob on the front right side of instrument).

-

# Place the cell in the sample compartment and align the guide mark on the cell with the guide

+

-

mark at the front of the sample compartment. Press the cell firmly into the sample compartment and close the lid.

+

-

# Adjust the meter to 100%T with the Transmittance/Absorbance Control (knob on the

+

-

front right side of instrument).

+

# Remove the cell from the sample compartment and empty the water.

# Remove the cell from the sample compartment and empty the water.

# Rinse the cell twice with small volumes of the solution to be measured and fill it with the solution.

# Rinse the cell twice with small volumes of the solution to be measured and fill it with the solution.

-

# Wipe the cell with a tissue and insert the cell into the sample compartment. Align the guide

+

# Wipe the cell with a tissue and insert the cell into the sample compartment. Align the guide marks and close the lid.

-

marks and close the lid.

+

# Read the appropriate value (%T or A) from the meter.

# Read the appropriate value (%T or A) from the meter.

# Remove the cell from the sample compartment and repeat steps 9 through 11 for any remaining sample solutions.

# Remove the cell from the sample compartment and repeat steps 9 through 11 for any remaining sample solutions.

To Use

The spec has two filters that you switch between using a lever on the bottom of the spec's left side. For 600 nm, use the position on the left.

while the spec is empty & the cap is on, set transmittance to 1 using the left knob

Insert blank & cover with black cap

Set transmittance to 100 with the right knob

Switch mode to absorbance

Absorbance for the blank should now read 0.

Measure absorbance for your sample

Keep tube orientation the same each time you measure in case of any unevenness.

Make sure the test tube is clean. Wipe it off if needed.

In Amanda and Janet's experience, the tube spec reads a higher absorbance than the rectangular 1 cm cuvette spectrophotometers.

Manual's Version of Instructions

Turn on the SPECTRONIC® 20+ by turning the Power Switch/Zero Control (knob on the left side of instrument) clockwise. Allow the spectrophotometer to warm up for at least 15 minutes to stabilize.

After the warmup period, set the desired wavelength with the Wavelength Control Knob.

Set the filter lever to the appropriate position for the selected wavelength (not required for SPECTRONIC® 20).

Adjust the meter to 0%T with the Power Switch/Zero Control (knob on the front left side of instrument). Make sure the sample compartment is empty and the cover is closed.

Fill a clean cell with water (or blank solution) and wipe the cell with a tissue to remove liquid droplets, dust and fingerprints.

Place the cell in the sample compartment and align the guide mark on the cell with the guide mark at the front of the sample compartment. Press the cell firmly into the sample compartment and close the lid.

Adjust the meter to 100%T with the Transmittance/Absorbance Control (knob on the front right side of instrument).

Remove the cell from the sample compartment and empty the water.

Rinse the cell twice with small volumes of the solution to be measured and fill it with the solution.

Wipe the cell with a tissue and insert the cell into the sample compartment. Align the guide marks and close the lid.

Read the appropriate value (%T or A) from the meter.

Remove the cell from the sample compartment and repeat steps 9 through 11 for any remaining sample solutions.

When all measurements are completed, turn off the spectrophotometer by turning the Power Switch/Zero Control counterclockwise until it clicks.